Free Astronomy Magazine November-December 2020

43 NOVEMBER-DECEMBER 2020 ASTROBIOLOGY ations in the amplitude of the sent radio wave. A valid alternative was devised in the 1930s by the American engineer Edwin Howard Armstrong, who developed the fre- quency modulation technique that is both much less subject to interference and more efficient in various applications. This is why any alien technological civilization could be expected to choose to broadcast on FM rather than other radio bands. This, of course, is a terrestrial opinion, although the electromagnetic spectrum in general can be considered a universal means of investiga- tion and communication. We don’t know why Tremblay and Tingay decided to center their latest survey on the constellation Vela. In their article published in PASA, they em- phasize the presence in this region of six known exoplanets, at which their listening was particularly attentive. However, as al- ready mentioned, the survey included about 10 million stars, and therefore likely millions of other unknown exoplanets. It would not have been easy to find the source of any FM I nfographic of the electromag- netic spectrum, which includes the levels of pen- etration of the various forms of radiation in the Earth’s atmos- phere.